Method and apparatus for casting liquid metals

ABSTRACT

Apparatus for casting metal including a furnace, a refractory obliquely ascending trough connected at its lower end to the furnace, a travelling field inductor extending along the trough length for conveying metal up the trough from the furnace, and a casting mould removably attached to the upper end of the trough. The mould is provided with a trough shaped entry which merges into the mould ingate and which forms an extension of the trough when the mould is attached to the trough. The metal is preferably conveyed up the trough at a rate equal to or greater than the rate that the mould will accept the metal.

United States Patent von Starck Apr. 30, 1974 [54] METHOD AND APPARATUS FOR CASTING 3,534,886 10/197O von gtarcleun 164/49 UX L U ME 3,696,858 10/1972 Seulen et a1. 164/4 G [75] Inventor: Axel von Starck, Grossberghausen, Primary Examiner charles W Lanham Germany Assistant Examiner-D. C. Reiley, 111 [73] Assignee: AEG-Elotherm G.m.b.H., Attorney, Agent, or FirmCushman, Darby &

Remscheid, Hasten, Germany Cushman [22] Filed: Jan. 12, 1973 ABSTRACT [21] Appl' 322944 Apparatus for casting metal including a furnace, a refractory obliquely ascending trough connected at its [30] Foreign Application Priority Data lower end to the furnace, a travelling field inductor Mar. 17, 1972 Germany 2212924 extending ng the trough length for conveying metal up the trough from the furnace, and a casting mould 52 US. Cl 1154/49, 164/133, 164/147 removably attached to the pp end Of the trough- [51] Int. Cl B22d 27/02 The mould is provided with a trough shaped entry [58] Field of Search 164/49, 133, 147, 250, hi h merges in the mould ingate and which forms 164/337, 363 an extension of the trough when the mould is attached to the trough. The metal is preferably conveyed up the [56] Refe Cit d trough at a rate equal to or greater than the rate that UNITED STATES PATENTS the ITlOUid W111 accept the metal.

3,515,898 6/1970 Von Starck 164/147 UX 9 Claims, 1 Drawing Figure METHOD AND, APPARATUS FOR CASTING LIQUID METALS Method and Apparatus The invention relates to apparatus for casting liquid metals, particularly light metals, comprising a melting or holding furnace, an electromagnetic conveying trough forming a spout consisting of a refractory obliquely ascending trough and an electromagnetic travelling field inductor extending along the length of the trough, as well as at least one casting mould. The invention also relates to a method of operating this apparatus.

Arrangements of this kind have already been described, for instance in German Pat. Specifications Nos. 1,286,701 and 1,783,044 In these arrangements the liquid metal is driven from the furnace against gravity in the form of an open stream up a obliquely ascending trough by a travelling electromagnetic field and pours into the casting mould from the upper end of the trough. In order to ensure that the quantity of poured metal is precisely controlled, irrespectively, of the level of the liquid melt in the furnace, the windings of the travelling field inducto'r are subdivided into a permanently energised component winding near the bottom end of the trough, which propels the liquid metal to a given point along the length of the trough, and a component inductor winding at the upper end of the trough which is energized during the pour for only a predetermined period of time. This arrangement which is described in German Pat. Specification No. 1,286,701 enables a high degree of accuracy to be achieved with regard to the quantity of metal cast in each pour.

Every person skilled in the art knows that when casting from a manually controlled tiltable ladle it is often important during the pour to keep the ingate of the mould completelyfull of metal if an optimum quality casting is to be obtained, and that only when this is successfully done can the highest pouring rates be achieved and the danger removed of particles of slag or air being entrained into the mould.

For optimum results the pouring rate should vary in a particular way for each 'kind of mould. For instance, in the automatic casting equipment described in German Pat. Specification No. 1,783,044 (an Addition to No. 1,286,701) this is achieved in that during the period of energization of the componenet inductor winding at the upper end of the trough the effective intensity of the travelling field produced by said winding is controllably varied according to a preset program by means of a suitable voltage regulating device. This prior art equipment is particularly useful for the consecutive production of major numbers of castings, bearing in mind that the determination of the appropriate program of voltage control takes some time, which may often be quite substantial, several pours being needed simply for testing. If the number of consecutive castings is not very great or if the casting work as is often the case in jobbing foundries varies considerably with regard to the nature of the castings that are required, then the programming of the intensity of the travelling field will generally be less valuable.

It is the object of the present invention to provide automatic casting equipment comprising a melting or holding furnace with an electromagnetic conveyor trough as well as a method of casting capable of satisfying the demands of an optimum pour, namely that the ingate should nearly always be full without the need for making preliminary special adjustments according to the particular nature of the casting mould. Moreover, the contemplated equipment is also intended to be less expensive and complicated than the above described prior types of equipment.

, According to one aspect of this invention, the casting equipment is provided with connecting elements particularly for releasably attaching the casting mould to the upper end of the trough so that the casting mould itself has a trough-shaped entry which merges into the ingate and which forms an extension of the trough when the mould has been attached to the upper end of the trough. Between the trough and the trough-shaped entry of the mould at least one sill for dividing the liquid metal may be provided. Conveniently, this may be formed on one of the connecting elements. It is preferred that the connecting elements comprise a sealing plate which has an opening forming the sill.

In another preferred development of casting equipment according to the invention the gradient of the bottom of the conveying trough, as already .described in German Pat. Specification No. 1,286,701, may, in the zone of the final inductor pole at the upper end of the trough, be less than it's gradient elsewhere along the length of the trough.

According to another feature of the proposed casting equipment and as likewise already proposed in German Pat. Specification No. 1,286,701, the winding of the travelling field inductor is subdivided into a first component winding which adjoins the furnace vessel at the bottom end of the trough and which remains energized throughout the operation, and a second component winding which is associated with'the remainder of the trough and is energized in the course of the pour.

Finally the invention also concerns a method of operating the proposed casting equipment which consists in adjusting the field strength of the travelling field inductor to a level at which the conveying rate of the trough is equal to or exceeds the maximum rate of acceptance of liquid metal by the attached casting mould.

The invention will now be more particularly described with reference to the drawing-which schematically andin section shows a preferred embodiment of casting equipment according to the invention. Vessel 2 of a conventional holding furnace is mounted on a truck 1. On one side of this vessel an ascending trough 3 of an electromagnetic conveyor is provided. Trough 3 is closed on the top by a cover 4. The top of the furnace vessel 2 is likewise closed by a cover 5 which on its underside carries heating elements 6 for heating a metal charge 7 in furnace vessel 2. Below trough 3 is an inductor 8 for generating a travelling electromagnetic field. The inductor winding comprises a first component winding 9 adjacent the furnace vessel 2 and an adjoining second component winding 10 which extends to the upper end of the trough. The connections 11 for feeding the winding are preferably taken to the outside at the junction between the two components.

In the zone 12 of the last pole of the inductor at the upper end of the trough the bottom 13 of trough 3 levels off into the horizontal. Thus, the gradient of this part of the line the trough is less than elsewhere. At the upper end of the trough is a sealing plate 14 containing an opening forming a sill 15 which rises above the bottom 13 of the trough 3.

Sealing plate 14 permits a releasable connection which is at least substantially tight to be formed with a casting mould 16, which in this example is of the permanent type. For making this connection pneumatically-operated clamping elements (not shown in the drawing) are preferably provided between sealing plate 14 and mould 16. These clamping elements draw the assembly on the truck, comprising the holding furnace and conveyor trough towards mould 16 and connect these two units releasably together. Mould 16 has a trough-shaped entry 17 which forms a continuation of the trough when the end of the trough and the mould have been connected together, and which merges directly into the ingate 18.

The described casting equipment is preferably operated as follows:

The component winding 9 remains energized throughout the operation. The electromagnetic travelling field produced by this component winding propels the liquid metal from the furnace vessel 2up the trough to the point where the second component winding begins. This causes a stationary layer of metal 19 to form which heats upt the body of the trough 3 without itself cooling since it remains in a state of continuous mass exchange with the charge 7 inside the furnace.

When the upper end of the trough has been connected to the mould 16 the second component winding 10 is also energized and the liquid metal is thereby driven further up the trough to its upper end where it flows over sill into trough-shaped entry 17 of the mould l6 and thence into the ingate 18. The intensity of the travelling field produced by the inductor is adjusted until the maximum rate of flow up the trough exceeds the maximum rate of acceptance of the metal into the mould. Under such conditions a layer ofliquid metal will form in the trough and in the trough-shaped mould entry very soon after pouring begins, this layer having the contour indicated by a chain line 20 in the drawing at a level which substantially depends only upon the performance of the trough. This level will not be greatly exceeded even when the mould is completely filled, since a state will be reached at which liquid metal which had been driven up the bottom of the trough where it was exposed to a powerful travelling field begins to flow back again after reaching zones where the intensity of the field is less and no longer sufficient to keep it at the top. Consequently, disregarding a short period of time when starting up, the ingate 18 will always be kept full throughout the continuation of the pour and casting conditions will be an optimum.

When the mould has been thus filled the second component winding 10 is switched off. This allows the liquid metal to flow back from the mould entry 17 into the trough until the conditions shown in the drawing have been restored. The connection between the upper end of the trough and the mould can be undone and a fresh mould which has been prepared for the next pour can take the place of the full mould. The moulds may be mounted on a turntable or travelling conveyor which permits them to be carried into register with the upper end of the trough in succession.

Instead of using permanent moulds, sand moulds can be used in which case the seal between the mould and the upper end of the trough would conveniently be pro duced by pressing a sealing element attached to the upper end of the trough against or into the relatively soft moulding sand.

Many changes and modifications in the abovedescribed embodiment of this invention can of course be made without departing from the scope of the invention. Accordingly, that scope is intended to be limited only by the scope of the appended claims.

What is claimed is:

1. ln apparatus for casting liquid metals having a furnace and an electromagnetic conveying trough forming a spout and consisting of a refractory, obliquely ascending trough and an electromagnetic travelling field inductor extending along the length of the trough, and at least one casting mould with an ingate, the improvement comprising connecting means for attaching the casting mould to the upper end of the trough wherein the casting mould has a trough-shaped entry which merges into the mould ingate, and which forms an extension of the trough with the mould attached to the upper end of the trough. i

2. In apparatus according to claim 1, the further improvement wherein the connecting means are releasable.

3. In apparatus according to claim 1, the further improvement comprising a sill for dividing the liquid metal between the trough and the trough-shaped entry into the mould.

4. In apparatus according to claim 3, the further improvement wherein connecting means includes a sealing plate having an opening which forms the sill.

5. In apparatus according to claim 1, the improvement wherein the gradient of the bottom of the conveying trough in the zone of the last inductor pole at the upper end of the trough is less than its gradient elsewhere along the length of the trough.

6. In apparatus according to claim 1, the further improvement wherein the winding of the travelling field inductor is subdivided into a first component winding which adjoins the furnace vessel at the bottom end of the trough, and which remains energized throughout the operation, and a second component winding which is associated with the remainder of the trough and which is energized in the course of the pour.

7. Apparatus for casting liquid metals comprising:

a furnace for holding liquid metal,

an electromagnetic trough connected to said furnace and including a refractory obliquely ascending trough up which metal is transported from said furnace, an electromagnetic travelling field inductor extending along the length of said trough and pouring spout formed on the end of said trough remote from said furnace, and

means for coupling said spout to a mould.

8. Apparatus as in claim 7 further including said mould and wherein said mould has a trough shaped entry which merges into a mould ingate.

9. A method of casting liquid metals comprising:

attaching a mould having an ingate and a trough shaped entry to the upper end of an obliquely ascending trough so that the entry forms an extension of the trough,

generating a travelling electromagnetic field to cause liquid metal to be conveyed from a furnace up the trough and into the mould via said entry, and controlling the field strength of travelling field so that the conveyor rate of the trough exceeds or is equal to the maximum rate which the attached mould will accept. 

1. In apparatus for casting liquid metals having a furnace and an electromagnetic conveying trough forming a spout and consisting of a refractory, obliquely ascending trough and an electromagnetic travelling field inductor extenDing along the length of the trough, and at least one casting mould with an ingate, the improvement comprising connecting means for attaching the casting mould to the upper end of the trough wherein the casting mould has a trough-shaped entry which merges into the mould ingate, and which forms an extension of the trough with the mould attached to the upper end of the trough.
 2. In apparatus according to claim 1, the further improvement wherein the connecting means are releasable.
 3. In apparatus according to claim 1, the further improvement comprising a sill for dividing the liquid metal between the trough and the trough-shaped entry into the mould.
 4. In apparatus according to claim 3, the further improvement wherein connecting means includes a sealing plate having an opening which forms the sill.
 5. In apparatus according to claim 1, the improvement wherein the gradient of the bottom of the conveying trough in the zone of the last inductor pole at the upper end of the trough is less than its gradient elsewhere along the length of the trough.
 6. In apparatus according to claim 1, the further improvement wherein the winding of the travelling field inductor is subdivided into a first component winding which adjoins the furnace vessel at the bottom end of the trough, and which remains energized throughout the operation, and a second component winding which is associated with the remainder of the trough and which is energized in the course of the pour.
 7. Apparatus for casting liquid metals comprising: a furnace for holding liquid metal, an electromagnetic trough connected to said furnace and including a refractory obliquely ascending trough up which metal is transported from said furnace, an electromagnetic travelling field inductor extending along the length of said trough and pouring spout formed on the end of said trough remote from said furnace, and means for coupling said spout to a mould.
 8. Apparatus as in claim 7 further including said mould and wherein said mould has a trough shaped entry which merges into a mould ingate.
 9. A method of casting liquid metals comprising: attaching a mould having an ingate and a trough shaped entry to the upper end of an obliquely ascending trough so that the entry forms an extension of the trough, generating a travelling electromagnetic field to cause liquid metal to be conveyed from a furnace up the trough and into the mould via said entry, and controlling the field strength of travelling field so that the conveyor rate of the trough exceeds or is equal to the maximum rate which the attached mould will accept. 